﻿// This file is from Zio - https://github.com/xoofx/zio
// and is licenced under the BSD 2-Clause "Simplified" License:
//
// Copyright (c) 2017-2021, Alexandre Mutel
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without modification
// , are permitted provided that the following conditions are met:
//
// 1. Redistributions of source code must retain the above copyright notice, this
//    list of conditions and the following disclaimer.
//
// 2. Redistributions in binary form must reproduce the above copyright notice,
//    this list of conditions and the following disclaimer in the documentation
//    and/or other materials provided with the distribution.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
// WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
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// SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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using System.Text;
using System.Text.RegularExpressions;

namespace OpenSage.IO;

internal readonly struct SearchPattern
{
    private static readonly char[] SpecialChars = { '?', '*' };

    private readonly string? _exactMatch;
    private readonly Regex? _regexMatch;

    /// <summary>
    /// Tries to match the specified path with this instance.
    /// </summary>
    /// <param name="name">The path to match.</param>
    /// <returns><c>true</c> if the path was matched, <c>false</c> otherwise.</returns>
    public bool Match(string name)
    {
        if (name is null)
        {
            throw new ArgumentNullException(nameof(name));
        }
        // if _execMatch is null and _regexMatch is null, we have a * match
        return _exactMatch != null ? _exactMatch == name : _regexMatch is null || _regexMatch.IsMatch(name);
    }

    public SearchPattern(string searchPattern)
    {
        if (searchPattern is null)
        {
            throw new ArgumentNullException(nameof(searchPattern));
        }

        _exactMatch = null;
        _regexMatch = null;

        // Optimized path, most common case
        if (searchPattern is "*")
        {
            return;
        }

        searchPattern = searchPattern.Replace('\\', '/');
        if (searchPattern.Contains('/'))
        {
            throw new NotSupportedException();
        }

        int startIndex = 0;
        int nextIndex;
        StringBuilder? builder = null;
        while ((nextIndex = searchPattern.IndexOfAny(SpecialChars, startIndex)) >= 0)
        {
            if (builder is null)
            {
                builder = new StringBuilder();
                builder.Append('^');
            }

            var lengthToEscape = nextIndex - startIndex;
            if (lengthToEscape > 0)
            {
                var toEscape = Regex.Escape(searchPattern.Substring(startIndex, lengthToEscape));
                builder.Append(toEscape);
            }

            var c = searchPattern[nextIndex];
            var regexPatternPart = c == '*' ? "[^/]*" : "[^/]";
            builder.Append(regexPatternPart);

            startIndex = nextIndex + 1;
        }
        if (builder is null)
        {
            _exactMatch = searchPattern;
        }
        else
        {
            var length = searchPattern.Length - startIndex;
            if (length > 0)
            {
                var toEscape = Regex.Escape(searchPattern.Substring(startIndex, length));
                builder.Append(toEscape);
            }

            builder.Append('$');

            var regexPattern = builder.ToString();
            _regexMatch = new Regex(regexPattern, RegexOptions.IgnoreCase);
        }
    }
}
